Similar sensorimotor transformations control balance during standing and walking

Standing and walking balance control in humans relies on the transformation of sensory information to motor commands that drive muscles. Here, we evaluated whether sensorimotor transformations underlying walking balance control can be described by task-level center of mass kinematics feedback similar to standing balance control. We found that delayed linear feedback of center of mass position and velocity, but not delayed linear feedback from ankle angles and angular velocities, can explain reactive ankle muscle activity and joint moments in response to perturbations of walking across protocols (discrete and continuous platform translations and discrete pelvis pushes). Feedback gains were modulated during the gait cycle and decreased with walking speed. Our results thus suggest that similar task-level variables, i.e. center of mass position and velocity, are controlled across standing and walking but that feedback gains are modulated during gait to accommodate changes in body configuration during the gait cycle and in stability with walking speed. These findings have important implications for modelling the neuromechanics of human balance control and for biomimetic control of wearable robotic devices. The feedback mechanisms we identified can be used to extend the current neuromechanical models that lack balance control mechanisms for the ankle joint. When using these models in the control of wearable robotic devices, we believe that this will facilitate shared control of balance between the user and the robotic device.

Download Full-text

Similar sensorimotor transformations control balance during standing and walking

10.1101/2020.09.30.320127 ◽

2020 ◽

Author(s):

Maarten Afschrift ◽

Friedl De Groote ◽

Ilse Jonkers

Keyword(s):

Gait Cycle ◽

Walking Speed ◽

Balance Control ◽

Center Of Mass ◽

Control Mechanisms ◽

Sensorimotor Transformations ◽

Robotic Devices ◽

Walking Balance ◽

Mass Position ◽

Task Level

AbstractStanding and walking balance control in humans relies on the transformation of sensory information to motor commands that drive muscles. Here, we evaluated whether sensorimotor transformations underlying walking balance control can be described by task-level center of mass kinematics feedback similar to standing balance control. We found that delayed feedback of center of mass position and velocity, but not local feedback of joint positions and velocities, can explain reactive ankle muscle activity and joint moments in response to perturbations of walking across protocols (discrete and continuous platform translations and discrete pelvis pushes). Feedback gains were modulated during the gait cycle and decreased with walking speed. Our results thus suggest that similar task-level variables, i.e. center of mass position and velocity, are controlled across standing and walking but that feedback gains are modulated during gait to accommodate changes in body configuration during the gait cycle and in stability with walking speed. These findings have important implications for modelling the neuromechanics of human balance control and for biomimetic control of wearable robotic devices. The feedback mechanisms we identified can be used to extend the current neuromechanical models that lack balance control mechanisms for the ankle joint. When using these models in the control of wearable robotic devices, we believe that this will facilitate shared control of balance between the user and the robotic device.

Download Full-text

Sensorimotor feedback based on task-relevant error robustly predicts temporal recruitment and multidirectional tuning of muscle synergies

Journal of Neurophysiology ◽

10.1152/jn.00684.2012 ◽

2013 ◽

Vol 109 (1) ◽

pp. 31-45 ◽

Cited By ~ 20

Author(s):

Seyed A. Safavynia ◽

Lena H. Ting

Keyword(s):

Sagittal Plane ◽

Balance Control ◽

Center Of Mass ◽

The Body ◽

Muscle Synergy ◽

Muscle Synergies ◽

Muscle Coordination ◽

Initial State ◽

Sensorimotor Feedback ◽

Task Level

We hypothesized that motor outputs are hierarchically organized such that descending temporal commands based on desired task-level goals flexibly recruit muscle synergies that specify the spatial patterns of muscle coordination that allow the task to be achieved. According to this hypothesis, it should be possible to predict the patterns of muscle synergy recruitment based on task-level goals. We demonstrated that the temporal recruitment of muscle synergies during standing balance control was robustly predicted across multiple perturbation directions based on delayed sensorimotor feedback of center of mass (CoM) kinematics (displacement, velocity, and acceleration). The modulation of a muscle synergy's recruitment amplitude across perturbation directions was predicted by the projection of CoM kinematic variables along the preferred tuning direction(s), generating cosine tuning functions. Moreover, these findings were robust in biphasic perturbations that initially imposed a perturbation in the sagittal plane and then, before sagittal balance was recovered, perturbed the body in multiple directions. Therefore, biphasic perturbations caused the initial state of the CoM to differ from the desired state, and muscle synergy recruitment was predicted based on the error between the actual and desired upright state of the CoM. These results demonstrate that that temporal motor commands to muscle synergies reflect task-relevant error as opposed to sensory inflow. The proposed hierarchical framework may represent a common principle of motor control across motor tasks and levels of the nervous system, allowing motor intentions to be transformed into motor actions.

Download Full-text

DUAL-TASK BALANCE CONTROL IN ADOLESCENT ATHLETES FOLLOWING CONCUSSION

Orthopaedic Journal of Sports Medicine ◽

10.1177/2325967120s00152 ◽

2020 ◽

Vol 8 (4_suppl3) ◽

pp. 2325967120S0015

Author(s):

Tracy Zaslow ◽

Camille Burton ◽

Nicole M. Mueske ◽

Adriana Conrad-Forrest ◽

Bianca Edison ◽

...

Keyword(s):

Dual Task ◽

Verbal Fluency ◽

Walking Speed ◽

Balance Control ◽

Dynamic Balance ◽

Center Of Mass ◽

Quiet Standing ◽

Return To Play ◽

Treatment Protocols ◽

Single Task

Background: Previous research has identified deficient dual-task balance control at the time of return to play (RTP) and possible worsening after RTP in older adolescents/young adults with concussion. These findings have not been investigated in younger patients with concussion. Hypothesis/Purpose: We hypothesized that concussed adolescents would have slower walking speed and increased medial-lateral (ML) center of mass (COM) movement, which would normalize by the time of RTP but worsen after resuming activity. Methods: 13 adolescent concussion patients (7 male; age 10-17 years) were prospectively evaluated at their initial visit (IV) (mean 18, range 4-43 days post-concussion), at RTP clearance (mean 46, range 12-173 days post-concussion), and one month later (mean 26, range 20-41 days post-RTP) along with 11 controls (3 male) seen for similarly timed visits. Standing balance was assessed using range and root mean squared (RMS) COM motion in the anterior-posterior (AP) and ML directions during standing on both legs with eyes open while performing quiet standing, dual-task audio Stroop, side-to-side head turns, and side-to-side thumb tracking tasks. Dynamic balance was assessed using walking speed and COM ML range and velocity during walking alone and with side-to-side head turns and verbal fluency (reciting words starting with “F”) dual tasks. Patients were compared against controls using t-tests, and changes over time were evaluated using linear mixed-effects regression. Results: During standing, patients had higher COM ML RMS than controls at IV during head turns and higher COM AP range during thumb tracking. COM ML motion decreased from IV to RTP (head turns range -6.5mm, p=0.058; head turns RMS -16.8mm, p=0.002; thumb range 9.2mm, p=0.012) and increased from RTP to 1 month follow-up (head turns RMS +10.0mm, p=0.040; Stroop RMS +8.4mm, p=0.086). Patients walked slower than controls at IV during all tasks, and COM ML range was higher in patients vs. controls during verbal fluency at IV and RTP. Walking speed increased from IV to RTP during verbal fluency (+7.8cm/s, p=0.044), from RTP to post-RTP in single task walking (+6.1cm/s, p=0.041), and at each successive visit during head turns (+6.0cm/s and +6.5cm/s, p<0.07). COM ML range also decreased in patients from IV to RTP with verbal fluency (-14.7mm, p=0.011) and from RTP to post-RTP in single task walking ( 4.0mm, p=0.061). Conclusion: Adolescent concussion patients had deficits in static and dynamic balance control at initial presentation. This tended to improve by RTP and only worsened post-RTP for dual-task ML control during standing, suggesting that current conservative treatment protocols are appropriate.

Download Full-text

Simulation Analysis of Impulsive Ankle Push-Off on the Walking Speed of a Planar Biped Robot

Frontiers in Bioengineering and Biotechnology ◽

10.3389/fbioe.2020.621560 ◽

2021 ◽

Vol 8 ◽

Author(s):

Qiaoli Ji ◽

Zhihui Qian ◽

Lei Ren ◽

Luquan Ren

Keyword(s):

Ankle Joint ◽

Gait Cycle ◽

Walking Speed ◽

Simulation Analysis ◽

Center Of Mass ◽

Biped Robot ◽

Maximum Speed ◽

Motion Patterns ◽

Fluctuation Amplitude ◽

Instantaneous Speed

Ankle push-off generates more than 80% positive power at the end of the stance phase during human walking. In this paper, the influence of impulsive ankle push-off on the walking speed of a biped robot is studied by simulation. When the push-off height of the ankle joint is 13 cm based on the ground (the height of the ankle joint of the swing leg) and the ankle push-off torque increases from 17 to 20.8 N·m, the duration of the swinging leg actually decreases from 50 to 30% of the gait cycle, the fluctuation amplitude of the COM (center of mass) instantaneous speed of the robot decreases from 95 to 35% of the maximum speed, and the walking speed increases from 0.51 to 1.14 m/s. The results demonstrate that impulsive ankle push-off can effectively increase the walking speed of the planar biped robot by accelerating the swing leg and reducing the fluctuation of the COM instantaneous speed. Finally, a comparison of the joint kinematics of the simulation robot and the human at a normal walking speed shows similar motion patterns.

Download Full-text

Effect of Multisession Progressive Gait-Slip Training on Fall-Resisting Skills of People with Chronic Stroke: Examining Motor Adaptation in Reactive Stability

Brain Sciences ◽

10.3390/brainsci11070894 ◽

2021 ◽

Vol 11 (7) ◽

pp. 894

Author(s):

Shamali Dusane ◽

Tanvi Bhatt

Keyword(s):

Postural Stability ◽

Walking Speed ◽

Balance Control ◽

Center Of Mass ◽

Chronic Stroke ◽

Treadmill Walking ◽

Compensatory Stepping ◽

Lift Off ◽

Clinical Measures ◽

Reactive Balance

Background: This study examined whether a multisession gait-slip training could enhance reactive balance control and fall-resisting skills of people with chronic stroke (PwCS). Methods: A total of 11 PwCS underwent a four-week treadmill-based gait-slip training (four sessions). Pre- and post-training assessment was performed on six intensities of gait-slips (levels 1–6). Training consisted of 10 blocks of each progressively increasing intensity (four trials per block) until participants fell at >2 trials per block (fall threshold). In the next session, training began at a sub-fall threshold and progressed further. Fall outcome and threshold, number of compensatory steps, multiple stepping threshold, progression to higher intensities, pre- and post-slip center of mass (CoM), state stability, clinical measures, and treadmill walking speed were analyzed. Results: Post-training, PwCS demonstrated a reduction in falls and compensatory steps on levels 5 and 6 (p < 0.05) compared to pre-training. While an increase in pre-slip stability was limited to level 6 (p < 0.05), improvement in post-slip stability at lift-off was noted on levels 2, 3, and 5 (p < 0.05) along with improved post-slip minimum stability on levels 5 and 6 (p < 0.05). Post-training demonstrated improved fall (p < 0.05) and multiple stepping thresholds (p = 0.05). While most participants could progress to level 4 between the first and last training sessions, more participants progressed to level 6 (p < 0.05). Participants’ treadmill walking speed increased (p < 0.05); however, clinical measures remained unchanged (p > 0.05). Conclusions: Multisession, progressively increasing intensity of treadmill-based gait-slip training appears to induce significant adaptive improvement in falls, compensatory stepping, and postural stability among PwCS.

Download Full-text

Effects of Balance Control Through Trunk Movement During Square and Semicircular Turns on Gait Velocity, Center of Mass Acceleration, and Energy Expenditure in Older Adults

PM&R ◽

10.1016/j.pmrj.2016.03.002 ◽

2016 ◽

Vol 8 (10) ◽

pp. 953-961 ◽

Cited By ~ 7

Author(s):

Sun-shil Shin ◽

Duk-hyun An ◽

Won-gyu Yoo

Keyword(s):

Older Adults ◽

Energy Expenditure ◽

Balance Control ◽

Center Of Mass ◽

Gait Velocity ◽

Trunk Movement

Download Full-text

Measurement Method Research on Inertial Parameters of Motor Assembly

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.437.663 ◽

2013 ◽

Vol 437 ◽

pp. 663-668

Author(s):

Ling Sun ◽

Peng Yu ◽

Tong Zhang

Keyword(s):

Measurement Method ◽

Center Of Mass ◽

Moment Of Inertia ◽

Balance Method ◽

Test Error ◽

Inertial Parameters ◽

Drive Motor ◽

Weight Method ◽

Mass Position

Inertial parameters of the motor assembly include its mass, CM (center of mass) position, moment of inertia and product of inertia. Taking one vehicle drive motor as the research object, its mass and CM position are measured by using weight method and moment balance method respectively. Its moment of inertia and product of inertia are measured by using three-wire pendulum. On the basis of analyzing the test error, this paper proposed specific measures to reduce the test error.

Download Full-text